Wire-winding apparatus



Nov. 6, 1951 H. F. KENNISON WIRE-WINDING APPARATUS 4 Sheets. 5heeJL l Filed July 4, 1945 nwe/wore j] Ze #71130,

Nov. 6, 1951 H. F. KENNISON WIRE-WINDING APPARATUS 4 Sheets-Sheet 2 Filed July 4; 1945 NVENTUR /fgg/t n/1130@ fr/pad ATTORNEY Nov. 6, 1951 Filed July 4, 1945 if@ t H. F. KENNISON WIRE-WINDING APPARATUS 4 Sheets-Sheet 5 INVENTOR ATTORNEY Nov. 6, 1951 H. F. KENNlsoN v 2,573,793

WIRE-WINDING APPARATUS Filed July 4, 1945 4 sheets-sheet 4 HTTRN EY Patented Nov. 6, 1951 WIRE -WIN DIN G APPARATUS Hugh Foster Kennison, Bloomfield, N. J., as-

signor tok Lock Joint Pipe Company, East Orange, N. J., a corporation of New Jersey Application July 4, 1945, Serial No. 603,178

Claims.

This invention relates to apparatus for winding wire around objects, and more particularly for applying a tensioned wrapping of wire in the production of pre-stressed pipe.

Among the objects of the invention is to provide an apparatus for wrapping a rotating body With wire having a known tension and for maintaining the tension during the entire wire Wrapping operation.

Another object is to provide a compact apparatus for tensioning a wire and for applying the tensoned wire as a helical winding about a rotating body.

Another object is to provide a Winding apparatus with a closed system through which the torque required to rotate an object being wrapped is balanced by a restraining torque acting upon the supply portion of the wire so that only a relatively small amount of power is required for accomplishing a winding operation.

Another object is to provide a wire winding apparatus employing a oating sheave by which tension is applied to a loop of wire intermediate a source of supply and an object being wrapped with the wire and wherein control is eiected to limit the extension of the loop and accompanying movement and displacement of the oating sheave during a Wire Winding operation.

Another object is to provide an apparatus capable of Winding wire under tension without injuring the wire or causing damage to any coating that it may have.

Another object is to provide a device for rotatively supporting a hollow core and for transmitting a rotating torque to the core, said device including a rotatable member engaging the exterior of the core and centering the core and a flange extending from the member inwardly of the core and supporting an inflatable element in contact with the interior of the core.

Another object of the invention is to provide a machine whereby a pre-stressed pipe may be constructed which has been wrapped under an exact tension.

Further and other objects of the invention will be hereinafter set forth in the accompanying specication and claims and illustrated in the drawings which show by way of illustration a preferred embodiment incorporating the principle of the invention and the best form in Which I have contemplated applying that principle.

Referring to the drawings,

Fig. 1A is a plan of the left end of an apparatus embodying the principle of the invention;

Fig. 1B is a plan of the right end of the apparatus;

Fig. 2A is a front elevation of the left end of the apparatus;

Fig. 2B is a front elevation of the right end of the apparatus;

Fig. 3 is a longitudinal section through a, differential unit;

Fig. 4 is a View on line lof Fig. 3;

Fig. 5 is a longitudinal section through a portion of a supporting ange by which one end of a pipe core is rotated;

Fig. 6 is a View similar to Fig. 5 showing a tube in inflated condition for engaging the interior of the core.

The principle of the present invention is useful in the production of pre-stressed pipe in which great strength is obtained and great economy eiiected by winding high tensile Wire under high tension about a pipe core, thereby compressing the core. The wire must be wrapped evenly and uniformly around the core under a denite predetermined tensicn and in a manner that will assure no loss of tension at any stage of the Winding operation. rI'he machine of this invention accomplishes this result. It also has the advantages of a compact organization capable of efficiently applying a tensioned Wrapping about any object.

All of the operating mechanisms and the object being wrapped are mounted and contained within an open box-like frame made up of structural steel elements, as shown in the drawings. In View of the fact that the object-supporting means is designed to accommodate a pipe core, such as a steel or concrete sleeve-like member, I shall refer herein to the object being wound as a core, it being understood that this term is used Without limitation and to identify any object about which a tensioned Winding is applied.

During a wire-winding operation a core I is mounted centrally or" the right end of the boxlikeirame. The core is supported at its ends from a pair of vertically disposed circular plates I I, I2, which have flanges I3 and I4, respectively,

engaging over the exterior end-portions of the core. Plate I is mounted upon and keyed to one end of shaft i5 for rotation therewith, and plate I2, at the other end of the core, is supported from aspindle it which is journalled for rotation in bearings Il and I8. Bearings Il and I8 are carried upon a carriage I9 having pairs of rollers 2), ZI which run on base I-beams 22 and 23 of the main frame.

For placing a core Ill in the machine the carriage I9 is displaced to the right of its position in Fig. 2B and the core is rolled over timber skids 24 and 25 to a central position between supportsprocket and chain connection 2'I with one of the K wheels supporting the carriage. The carriage is locked in the core-supporting position illustrated in Figs. 1B and 2B during a wire-winding operation.

Figs. 5 and 6 illustrate the manner which the left end of the core is supported by plate I I and flange I3. The core illustrated includes v'an'outer steel cylinder with joint rings welded thereto and an interior body of concrete. The end of the core is ,seated against plate II, and flange I3 engages the circumference of 'the bearing ring of the core. A ring 28 is xedly mounted 'on plate II, concentrically with flange I3. About this ring there is mounted a pneumatic tube 29 having a valve stem 34 by which it may be linflated. After the core is ymounted in place be'- tween the plates II and I2, the pneumatic tube is `cllistended by inflation to provide a rm connection between the interior "of th'e core 'and ring 28, as illustrated in Fig. l6. This manner of mounting and securing the core in place in the apparatus affords means for firmly gripping the core whereby the core-rotating torque is transmitted from flanged plate iI to the core during a wire-winding operation. 'A gripping connection similar to the pneumatic,V tube and ring may be used with plate I2 at the lother end of the core, but this is not indispensable since spindle I6 rotates freely in its bearings and the core is 'adequately supported by flange I4.

The drive for rotating the core originates from I 'a variable speed motor 3| which drives a speed reducer 32, a flexible coupling 33, and a shaft 34 which is mounted in bearings 35 and 36. Shaft 34 is affected by a torque substantially 'equal and opposite to the core-rotating torque as will be explained hereinafter. Shaft 34 carries a sprocket wheel '3l driving a sprocket chaint, and a sprocket wheel 39 which-is keyed to shaft `I 5 lupon which core-supporting and driving plate -I I is mounted. Shaft I5 jis journalled in bearings 4I), 4I.

VThe wire to be Vwound "uponfth'e Acore may be taken from a supply vspool (not shown). -It fis `threaded through -a light restraining brake '42 `from which it passes to a tapered drum4-3. Sevieral turns of the wire are placed about the tapered `drurn andronly sufcient restraintis applied Aby brake 42 to cinch the vwire about the drum. The drum is restrained against Vfree rotation but rotates suiciently to supply wire for application to the core. Wire-tensioning means is provided intermediate the drum and the core.

As shown in Figs. 1A and 2A, the wire leaving the drum passes over an idler 44 which guides the wire to a floating sheave 45 from whence it is delivered to a travelling guide-sheave 46 and then through an opened adjustable'clamp 41 to the core. The end of the wire is attached to the core by an anchor 48. As shown in the drawings, the core has been rotated a few times, during which travelling sheave 46 has vmoved to the right from a left hand position.

The pitch of the winding on the core is controlled by therate of movement of sheave 46. Sheave 46 is inounted'u'pon a carriage consisting 4 of a frame 49 supported at its ends by pairs of rollers 50, 5I. These rollers bear upon the inside anges of a pair of I-beams 52, 53 and travel thereover. These I-beams are parallel to the core and extend lengthwise of the apparatus for guiding the sheavela sufficient distance to wrap the longest 'core that may be mounted in the apparatus.

The rate of movement of travelling sheave 46 and frame 46 is controlled by a variable speed motor reducer unit 54 which drives a speed reducing unitw55 and a sprocket and chain connection 56. The driven sprocket 5l of this drive is mounted upon a shaft E8 to which is keyed a sprocket wheel 59. Bearings 5e and GI, which support shaft 58, are adjustable lengthwise of the machine for controlling the tension in chain 56.

ATravelling sheave 46 is moved by chain 62 which operates as an endless chain having its ends connected to carriage frame 49 at G3 and 64. The chain passes over a Vsprocket G5 at the right end of the apparatus. This sprocket is mounted on a shaft 66 journalled in adjustable bearings '6l and 68 by which the tension in chain B2 may be set. The upper reach of the chain between sprocket wheels 56 and 65 is supported against sagging on a web of a longitudinally extending I-beam 69.

The desired 'tension is applied to the loop of wire intermediate drum 43 and the core by restraining force applied to floating sheave 45. This sheave is rotatably mounted upon a vertical shaft I6 which extends upwardly from 'a carriage 'fr'ame II having pairs of rollers 'I2 and I3 engaging upper and lower flanges of channel members 74, l5. These channel members are part of the main frame and extend longitudinally thereof.

-A cable 'I6 is attached to the carriage by a yoke "Il fastened to shaft 1G. VCable E6 passes over an idler sheave I8 and has "attached to its lother end a spring 'I9 from which a weight 86 is supported. The amount of vmass represented by weight yBtl may be varied, as desired, by plac- 'ing l3cr removing additional weights, it being understood that the total mass required must be 'sii'ch as to effect a pull upon cable 'I6 equal to 'twice the amount of the tension desired in the wire being wound about the core.

During a wire-winding operation the wire intermediate tapered vspool 43 and the 'core is subjected to hi'g-h tensile stress and, disregarding for the moment the effect of 'movement Tof guide sheave 46, it is Aapparent -that -iioating sheave 45 would change its position as wire delivered from the "tapered drum becomes tensioned. If pro- Lvision were not made for automatically controlling the position 'of iloating sheave 45, a considerable length of track would have to be provided for the movement of the sheave. The mechanisms about to be described enable the lmovement of floating sheave 45 and the rise and fallo'f weight 80 to be restricted within narrow limits. kThese mechanisms include a differential unit capable of 'controlling the 'rate of rotation o'fdrum 43 "and a motor 'Sl whose operation is 'controlled to limit the displacement or extent of movement of the floating sheave las will be explained hereinafter. The differential unit is interposed between the drum 43 and gearing 62,

3,"w'hich is directly driven byshaft 34 andmotor 3|, The 'differential unit is supported by the sh'aft `I5, but all members thereof Vcan vrotate with respect to the shaft.

Shaft 34 has keyed to it a gear 82 which meshes with a gear 83 which is keyed to sleeve 84 of a differential unit, as best illustrated in Figs. 3 and 4. Sleeve 84 carries a bevel gear 85 of a differential gearing. Since the shaft I5 and the shaft 34 are directly connected together by the sprocket chain 38, and the sleeve 84 is directly connected to the shaft 34 by the gears 82 and 83, the gear 85 ofthe differential gearing is driven at a speed proportional to the speed of the shaft I5 but in the opposite direction. Gear 85 is engaged by bevel pinions 86 which are individually mounted on thrust bearings 81 carried by a spider worm gear 88. Four of these bevel pinions and thrust bearings are shown in Fig. 4. These bevel pinions 88 are engaged by a bevel gear 89 which is fast to a sleeve 99 to which tapered drum 43 is keyed. Spider worm gear 88 is carried by a differential housing 3 I, 92, which is attached to sleeves 93, 94, and bears on bronze bushings for free rotation about sleeves 84 and 99. The differential unit is located on shaft I5 by a pair of collars 95 and 96 which are pinned to the shaft.

With the ratio of gears 82 and 83 equal to the ratio of sprockets 31 and 39, when shaft 34 is rotated, shaft I5, which rotates the core,-and drum 43 will be rotated in the same direction and the speed of rotation of the core and of the drum will be the same so long as spider worm gear 83 is held in a stationary position. However, as wire is taken from drum 43 and it becomes subjected to elongation due to the applied tension, it is required that the rate of rotation of drum 43 be less than that of the core if the movement of floating sheave 45 is to be limited within a reasonable distance. Advantages of restricting the length of movement of sheave 45 include savings of time which otherwise would be required by stoppages of the apparatus for resetting the sheave periodically during a winding operation.

The rotation of spider worm gear 88 and its housing is controlled by a motor 91 which operates a worm 98 having engagement with the spider worm gear, With reference to the machine and relative size of core illustrated in the drawings, the direction of rotation of the motor 91 is such vas to drive the spider worm gear 89 in a clockwise direction as viewed from the right of Fig. 2A. As the wire is wound about the core I8 from left to right, some of the elongation of the wire between the drum 43 and the core II) is compensated for by the travel of the guide sheave 48 to the right, but the normal stretching of the wire is greater than the lineal travel of the guide sheave 45. There therefore remains an amount of stretch that can be compensated for by rotation of the drum 43 at such a rate as to provide an instantaneous speed of the drum less than that of the core I9. By driving the spider worm gear 88 clockwise (as viewed from the right of Fig. 2A) and at a speed less than that of the gear 85, the counterclockwise speed of' rotation of the bevel gear 83 will be less than the clockwise speed of rotation of the bevel gear 85, and the drum 43 will rotate at a counterclockwise speed less than the counterclockwise speed of the core I0. As illustrated in the drawings, motor 91 is operated from a switch 99, Fig. 2A, which is controlled by a pair of spaced stops IDU, IBI. These stops may be carried by carriage 1I or any other part which is movable in response to the movement of the carriage as, for example, Weight 80. As the wire leaving drum 43 elon- 6, gates, floating sheave 45 will move to the left under the pull of weight 88 and when stop IDU comes into contact with switch 99 the motor 91 is operated to lessen the rate of rotation of drum 43, whereupon weight 88 will be gradually raised until stop IOI comes into contact with switch 99 and causes the motor 91 to decrease the speed of rotation of the spider worm gear and thereby increase the speed of the drum 43. Drum 43 is continually rotated during a wire winding operation, but its speed of rotation is periodically diminished for moving floating sheave 45 to the right. matically controlling the drive for drum 43. The speed of rotation of the drum 43 can be controlled by constant or intermittent operation of the motor 91. It is preferred to use a variable speed motor 91 and to run the motor continuously. If a variable speed motor is used, it can be operated continuously to maintain a proper balance of the speed of the drum and of the core automatically to correct for changes in position of the sheave 45. Stops I0@ and 8l cause acceleration and deceleration, respectively, of the motor 91 to cause a hunting of the average running speed. If a direct current motor is employed, for example, a variable resistance can provide the electrical control. A constant speed motor may be used to operate the spider worm gear 88. If a constant speed motor is employed, its running speed should be greater than the average running speed required. In that case stops |00 and IGI, respectively, start and stop the motor as often as necessary for returning the sheave 45 to its right-hand position, Figs. 1A and 1B.

The core-driving torque of shaft I5 is derived from shaft 34 by means of sprocket connection 3B and is balanced through shaft 34 by the reacting torque transmitted from drum 43 to shaft 34 by the differential unit and gears 82 and 83. This arrangement provides a closed system of torques and although ninety horsepower might otherwise be required to rotate a core against a desired wire tension, in this closed system only a relatively small motor 3l is required for overcoming the inertia and friction of rotating parts. The auxiliary motor 31 is likewise relatively small since the relative speeds of drum 43 and core II] are nearly the same. Although the torque at this motor is high, the actual speed is extremely low with resultant low horsepower.

While a wire-winding operation is taking place, guide sheave 48 will travel lengthwise of the machine at such a speed as to impart a desired pitch to the wire about the core. When sheave 45 reaches the other end of the cere the operation of the machine is stopped and clamp 41 is adn justed by a thumb piece I3? to prevent the wire from losing tension in the machine when the wire is cut below clamp 41. For the purpose of anchoring the wire to the core, metallic sleeves of the type described in United States Patent 2,375,921 may be used, but any anchor suitable for fastening the wire may be employed. After the tensioned wire is fastened to the core, the wire may be cut between the core and the locked clamp 41. The next core to be wrapped with wire is rolled into and secured to the machine. The recently cut wire below clamp 41 is fastened to the newly positioned core and with the spacing mechanism reversed the core is tension-wrapped as previously described, except that it is wound from right to left. Since in winding the core from right to left the lineal travel of the guide Switch -99 provides a means for auto-A asfzavos sheave 46 adds to the corrective .compensation required for the stretching of the wire, the speed of rotation of the drum 43 will have to be slower than its speed of rotation during winding of the core from left to right. Consequently, .the spider worm gear S8 will be rotated slightly faster or more frequently (depending on whether the motor Si is a variable speed motor `or a constant speed motor) in a clockwise direction, `as viewed from the right of Fig. 2A, as compared to Yits operation when the winding is applied from left .to right along the core.

It is to be understood that the invention is susceptible of use for applying a winding or wrapping of practicallyany kind `of flexible tension element about 4a body `and -that various changes and modifications in construction, vform and relative arrangement 'of parts, which will now appear to those skilled .in the art, may .be made within the scope of the invention. Reference is, therefore, to be had to the appended claims for a definition of the limits .of #the finvention.

I claim:

1. In apparatus for winding wire on an object, Ithe combination of means yfor rotatably supporting van object, a rotatably-supported drum, lmeans -for rotating said object-supporting means, .dif- -ferential gearing having one gear driven .by said last-named means, a driving gear for said drum, and a diierential member geared to engage .both of said gears, means controlling the Arotation yof said diierential member to control ,the speed of rotation of said driving gear and drum, and

-means acting on the wire intermediate .-saididrum and object to apply and maintain a constant tension to the wire leaving saiddrum and-passing to said object even though the length of .wire between said drum and said objectchangesduring a wire-winding operation.

2. In apparatus for winding-wire lon an object, the combination of means lfor rotatably .supporting an object, a rotatably supported drum, means acting on the wire leaving `said drum and being applied to said object to maintainca constant-:tension on the wire irrespectiveo change lin1lcngth of the wire between the drum and the object during a winding operation, means :for .rotating said object-supporting means to wind .wire .on

said object carried thereby, differential .gearing r having one gear driven by said last-named means, a driving gear for said drum, anda differential member geared to -engageaboth of ,said gears, and means for controlling lthe .rotation of said differential member to control the .speed y of rotation of said drum relative to the vspeed of said object-supporting means.

3. In apparatus for winding wire on an object, the combination comprising means for rotating an object, a drum mounted for rotation on an axis coaxial with the axis of rotation of said object, means for applying tension in a loop of wire having reaches extending to saiddrumland to the object, means controlling the rotation-of said drum as wire is drawn therefrom,.said.last named means including dierential gearing hav- -ing one gear driven by saidvmeansiforrotating vsaid object, a drivinggear for-said drum,^an.da ydiiierential member geared to -engage both .of -said gears, and means controlling -therotation of said dierential member to -vary lthe -rate of -rotation of said drum.

4. In apparatus -forwinding a'wireonaniobject, the combination comprising means ivfor lmounting an--object Ifor rotation, means Afor =ro 1- I tating said object, a carriage, means carried by said carriage for guiding a wire onto lthe object, means for actuating said carriage in a direction substantially parallel to the axis of the object, a rotatably supported drum, a floating sheave for engaging `with a loop of line having one end eX.- tending to the object and the other end extend.- ing to said drum, a weight secured to said sheave for applying and maintaining a constant tension to the wire between said drum and said object during movement of said sheave, means for rotating said drum in the same direction as the direction of rotation of said object whereby wire leaving said drumis wound about the object, said last-named means including differential gearing having one gear driven by said means for rotating said object, a driving gear for said drum, and a differential member geared to engage both of said gears, and means controlling the rotation of said ,diierential member, said controlling means -being controlled by movement of said weighted means.

5. In apparatus for winding wire on an object,

fthe combination comprising means for mounting an object for rotation, a drum, means rotatably mounting said drum, common power means for rotating said object and said drum, gearing Ideriving power from said common power means and disposed intermediate said object and said drum whereby said object and said drum may be rotated at different instantaneous speeds, a movable sheave for engaging a loop .of .wire hay: ing one portion frictionally engaged by said drum and another portion yextending to said object, weighted means secured to said movable sheave vfor applying constant tension to said loop of wire, a carriage mounted for travel in a direction Vparallel to the axis of rotation of said object, a .sheave on said Carr-lage adapted for yreceiving wire from said Yloop of Wire and directing the wire to said object, and means independent 0f said power means for traversing said carriage lengthwise of s aid object for applying a helical .winding of tensioned wire about said object.

6. vIn apparatus for winding wire on an object, the combination comprising means for mounting an object for rotation, a drum, means rotatably mounting said drum coaxially with respect to the axis of rotation of said object, ypower {means .common to said object-mounting means and to .said drum-mounting means for rotating saidobject and yfor applying ra retarding torque to said drum, differential mechanism deriving power from said common power `means and disposed intermediate said object .and said drum whereby said .object and said drum may be rotated ,at

.diierent instantaneous speeds, motor means independent of said power Ymeans and having con.- nection with said differential mechanism for rchanging :the relative .instantaneous speeds of said object and said drum, a movable sheave for engaging a loop of wire having one portion fric- .tionallyengaged by said .drum and another por,- ition extending to said object, weighted means secured-:to said movable sheave `for applying conthe axis of rotation of said object, asheave on `said lcarriage adapted for receiving wire from said zloop oi wire and directing the wire to said object, a second motor means independent ofsaid powermeans for traversing said carriage length- `wiseof said object `for applying a helical .wind- :ing of ltensioned wire about said object, and

means controlledby .the movement of said movable sheave for controlling said first-named motor means to effect changes in the relative rates of rotation of said drum and said object.

7. In apparatus for winding wire on an object, the combination comprising means for mounting an object for rotation, a drum, means rotatably mounting said drum, power means common to said object-mounting means and to said drummounting means for rotating said object and for applying a retarding torque to said drum, differential mechanism deriving power from said common power means and disposed intermediate said object and said drum whereby said object and said drum may be rotated at diierent instantaneous speeds, motor means independent of said power means and having connection with said differential mechanism for changing the relative instantaneous speeds of said object and said drum, means for training the length of Wire between said drum and said object including a movable sheave mounted for travel lengthwise of the axis of rotation of said Object and a sheave mounted upon a carriage arranged to travel lengthwise of said object for delivering wire to said object, means attached to said movable sheave for imparting tension to said length of wire, means for traversing said carriage and said wire-delivering sheave lengthwise of the axis of rotation of said object at a lineal velocity different from the lineal velocity of said movable sheave, and electric circuit control means controlled by the movement of said movable sheave for controlling said motor means to change the instantaneous speeds of said drum and said object.

8. In apparatus for winding wire on an object, the combination comprising means for supporting an object for rotation, a rotatably supported drum, a movable sheave for engaging a loop of wire having reaches extending to said object and to said drum, force applying means attached to said sheave for maintaining a constant tension in the wire intermediate said drum and said object, track means parallel to the axis of rotation of said object, a carriage mounted for travel along said track means and carrying a second sheave engaging said tensioned wire between said drum and said object for guiding it onto said object, means for rotating said object and said drum at different instantaneous speeds, means controlling the instantaneous speeds of said drum with respect to said object, and means independent of said drum-and-object-rotating means for traversing said carriage along said track means.

9. In apparatus for applying a wrapping of tensioned wire about a pipe or other object to which one end of the wire is fastened, and the object is rotated as the wire is wrapped thereon, the combination comprising rotatable means for supporting the object, a drum around which the feeding portion of the wire passes and from which the wire travels to the object, rotatable "means for supporting said drum, said objectaccompanying movement of said sheave during the wrapping of wire about said object, a differential mechanism having one member connected to turn with said object-supporting means, another member connected to turn with said drumsupporting means, and a third member in geared engagement with said first and second members, means for rotating said object-supporting means and said rst-named member, the rotating torque transmitted by said last-named rotating means being balanced by the retarding torque of said drum acting on said wire as transmitted through said second-named. member and differential mechanism, means for controlling the rotation of said third member of said diierential unit to thereby control the speed of said drum with respect to the speed of said object and the rate of change in length of the wire between said drum and said object, a motor for operating said last-named means, and a controlling circuit for said motor for changing the rate of operation of said motor to thereby limit the travel of said movable sheave away from and towards said drum and said object.

10. In apparatus for applying a wrapping of tensioned wire about a pipe or other object to which one end of the wire is fastened, and the object is rotated as the wire is wrapped thereon, the combination comprising rotatable means for supporting the object, power means having direct connection with said object-supporting means for rotating the same at a given velocity to wrap wire about said object, a drum for receiving relatively untensioned wire which is snubbed around the drum and tensioned for delivery to said object, rotatable means for supporting said drum, means for guiding the wire onto said object, a sheave engaging and forming a loop in the wire between said drum and said object, a Weight carried by said sheave, said weight and said sheave being free to move except for the restraining eiect of the tensioned wire travelling from said drum to said object, means for applying a retarding torque against the free rotation of the drum-supporting means under the action of the tension in said loop of wire, said\lastnamed means including differential mechanism between said drum-supporting means and said object-supporting means with connections at opposite sides thereof with said object-rotating means and with said drum-supporting means, respectively, motor means for controlling the operation of said differential mechanism to cause the drum-supporting means to be rotated at a speed slower than the given velocity of the object-supporting means, and means responsive to the length of wire between said drum and said object for alternately changing and restoring the velocity ratio of said diierential mechanism to vary the speed of rotation of said drum-supporting means, periodically to change the length of wire between said drum and said object during a wire wrapping operation.

HUGH FOSTER KENNISON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,816,909 Larsen Aug. 4, 1931 2,012,208 Wildy Aug. 20, 1935 2,243,795 Eaddy May 27, 1941 2,313,618 Bridges Mar. 9, 1943 2,389,047 Heinz Nov. 13, 1945 

